1. Technical Field
The present invention relates to image quality improvement, and more particularly to a method of shoot suppression and an image quality improving apparatus.
2. Discussion of the Related Art
A transient improvement technique for increasing sharpness of an image signal reduces an edge transition time. In the case of a luminance signal, the transient improvement technique is referred to as a luminance transient improvement (LTI) technique.
Generally, the transient improvement technique is applied to reduce the transition time and thereby increase the sharpness of an image. In reducing the transmission time, there may be sideeffects related to overshoot and/or undershoot or distortion of the image.
FIG. 1 is a timing diagram illustrating an example of a conventional image quality improvement process.
Referring to FIG. 1, an original image signal A is inputted to an image quality improving apparatus. The image quality improving apparatus generates a first derivative signal B and a second derivative signal C from the input signal A. The image quality improving apparatus multiplies the first derivative signal B by the second derivative signal C to generate an adjustment signal D. Then, the image quality improving apparatus adds the input signal A and the adjustment signal D to generate a quality-improved image signal E.
The quality-improved image signal E has a shorter transition time than the original image signal A but also has an overshoot and an undershoot. The reduction of an edge transition time may sharpen an image but the overshoot and undershoot (shoots) may distort an original image and thus degrade image quality. As the transition time becomes shorter, undershoots or overshoots that occur in the conventional image quality improvement process become larger.